What Jaroslaw Kaczynski lacks in height, he more than makes up for in political acumen, audacity and clout which have kept him at the heart of Polish politics.

The feisty 71-year-old is widely considered Poland's ultimate powerbroker -- steering the government as leader of the right-wing Law and Justice (PiS) party from its Warsaw headquarters.

So far he has called the shots as a regular MP, but will now join the PiS-dominated government as a deputy prime minister in what commentators see as a bid to quell power struggles with his party's two smaller coalition parnters.

"The Chairman's Ear", a political satire, portrayed Kaczynski as a dishevelled, short and plump bachelor ruling his party, its government and ultimately Poland with an iron will, all while doting on his beloved cat.

Since taking office in 2015, Kaczynski's PiS has in many ways upended Polish politics, with observers saying it has crafted a central European brand of illiberal democracy similar to that forged by Viktor Orban in Hungary.

While critics including the European Union say the PiS's judicial reforms violate the rule of law, pushing Poland away from its European partners and ushering in a creeping authoritarianism, supporters hail its welfare measures, including a popular child allowance, pension and wage hikes, all aimed at creating an effective social safety net.

The leader of the PiS Party (Law and Justice) Jaroslaw Kaczynski dominates Polish politics as the country goes to polls Sunday
The leader of the PiS Party (Law and Justice) Jaroslaw Kaczynski dominates Polish politics as the country goes to polls Sunday AFP / JANEK SKARZYNSKI

Brushing aside criticism, Kaczynski says that far from undermining democracy, his party's judicial reforms are aimed at tackling corruption and removing the last vestiges of communism from the justice system.

A master of political intrigue since playing a behind-the-scenes role in the Solidarity trade union's dismantling of communism in Poland in 1989, Kaczynski is a highly combative and polarising figure.

On the campaign trail ahead of the October 2019 general election, he attacked Poland's LGBT community as a "threat" to traditional families and thanked a senior Catholic Polish clergyman for labelling the community a "rainbow plague".

During the 2015 campaign, as Europe was grappling with its biggest migrant crisis since World War II, Kaczynski claimed refugees were bringing "cholera to the Greek islands, dysentery to Vienna, various types of parasites" -- comments that critics said recalled the Nazi era.

The leader of the PiS Party (Law and Justice) Jaroslaw Kaczynski dominates Polish politics as the country goes to polls Sunday
The leader of the PiS Party (Law and Justice) Jaroslaw Kaczynski dominates Polish politics as the country goes to polls Sunday AFP / JANEK SKARZYNSKI

Since taking power, the PiS has pursued its vision of a conservative, Catholic Poland that is vigilant of its interests abroad, but critics warn that its inward-looking, nationalist approach has triggered a rise in xenophobia.

Some who know him well say that Kaczynski, who speaks only Polish and rarely travels abroad, sees danger in anything foreign.

He has long been a fierce critic of the strong brand of EU federalism championed by powerhouses Germany and France and is among a growing number of populist leaders advocating a reform agenda for the bloc that favours national sovereignty over federalism.

In 2010, Kaczynski was deeply scarred by the death of his identical twin brother Lech Kaczynski, then Poland's president, who was among 96 senior officials killed when his jet crashed in Smolensk in eastern Russia.

Kaczynski has long insisted that the crash was no accident even though Polish and Russian investigators found that pilot error, bad weather and poor air-traffic control were to blame.

The Kaczynski twins grabbed the limelight with a short stint as child stars, starring in the popular 1962 Polish film "The Two Who Stole The Moon", about a couple of scheming urchins.

A cat lover who never married, Jaroslaw lived with his mother, with whom he was very close, until her death in 2013.

Kaczynski has dedicated his life to politics. He co-founded the PiS with Lech in 2001 and went on to serve as prime minister in 2006 and 2007 while his brother was president.

A lawyer and strident anti-communist in the 1970s, Kaczynski joined dissidents in the underground opposition that blossomed into the Solidarity movement in 1980, which sparked the fall of the communist regime nine years later.

He was close to Solidarity leader Lech Walesa, who was elected president in 1990, but has since accused him of being a former communist agent, a claim Walesa has fiercely denied.